In The Happy Christian Jared Waterbury claims that piety is the hallmark of a Christian. Piety produces purer and more plentiful joys. "Rejoice in the Lord" reveals God as the foundation of pious joy, the source of all true felicity. The joy of salvation is unparalleled with joyous prospects of eternal life with Him. Piety will not make you happy in life or triumphant in death unless it fully rules your life.